Conventional circulators, such as those disclosed in U.S. Pat. No. 5,574,596 issued Nov. 12, 1996 to Yihao Cheng; and U.S. Pat. No. 5,909,310 issued Jun. 1, 1999 to Wei-Zhong Li et al are three port devices that direct light entering a first port to a second port, and light entering the second port back to a third port. Generally, the light entering the first port is divided into two sub-beams, the polarization of which is manipulated to enable the sub-beams to pass through a polarization-dependent beam director along a first path, after which the sub-beams are recombined for output. Similarly, light entering the second port is divided into two sub-beams, but the polarization thereof is manipulated so that the sub-beams pass through the polarization-dependent beam director along a second path, different than the first, whereby the sub-beams are recombined at the third port.
Unfortunately, these conventional circulators are designed to recombine the light beam traveling from the first port to the second port, and to receive a combined light beam at the second port for travel to the third port.
An object of the present invention is to overcome the shortcomings of the prior art by providing an optical circulator that outputs and receives like-polarized sub-beams instead of a single combined beam at the second port.